1. Field of the Invention
The present invention relates to a communication system, and more particularly to a method for receiving a signal in a communication system and a system therefor.
2. Description of the Related Art
In the next generation communication systems, research is actively being conducted to provide users with services having various Qualities of Service (QoS) at a high speed. A representative next-generation communication system is known as an Institute of Electrical and Electronics Engineers (IEEE) 802.16 communication system.
The IEEE 802.16 communication system is a communication system (hereinafter, an OFDM/OFDMA communication system) employing an Orthogonal Frequency Division Multiplexing (OFDM)/Orthogonal Frequency Division Multiple Access (OFDMA) scheme.
The OFDM/OFDMA communication system prevents signals from being distorted by using guard intervals in order to prevent signal interference between adjacent bands. The guard intervals may be also used to prevent signal interference between frequency bands allocated to providers. Also, when the OFDM/OFDMA communication system supports a Time Division Duplex (TDD) scheme, Transmit Transition Gaps (TTGs) and Receive Transition Gaps (RTGS) exist between uplink subframes and downlink subframes. The TTGs and RTGs are gaps required for switching between uplinks and downlinks. Since the guard interval between frequency bands occupies only one band, but is not used for signal transmission, the efficiency of resources is degraded as more resources are used for the guard interval.
Meanwhile, in a communication system, it is important to remove signal interference through channel estimation in order to enhance the performance of the system. The channel estimation is achieved using a reference signal, e.g., a preamble or a pilot signal. In the channel estimation, as the amount of reference signals increases, the channel estimation can be more accurate. However, as the amount of reference signals increases, the amount of resources to be used for data transmission decreases. This acts as an overhead in the communication system. Therefore, it is necessary to develop a method of accurately estimating a channel using a limited reference signal.